Scattered Radiation Correction in CT via Movable Grid
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Solution Overview
Problem
Existing computed tomography methods fail to effectively correct scattered radiation, especially in cases of large gradients, leading to inaccuracies in material density reconstruction and artifacts in radiographs.
Innovation Solution
A method involving a grid structure that divides x-ray radiation into partial beams, altering its position to capture both irradiated and non-irradiated regions, generating bright-field and dark-field radiographs, and subtracting the dark-field radiograph from the bright-field radiograph to correct for scattered radiation, thereby improving radiation correction without the need for additional grid installation or removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If scattered radiation correction methods are applied using movable modulator fields or rasterized beams, then scattered radiation artifacts are reduced, but measurement time increases due to multiple recording geometries required
Solution Approach 1:
The patent applies the dynamics principle by making the grid structure movable along the beam path. The grid can be dynamically positioned between different grid positions (first and second positions) to alternatively transmit and attenuate x-ray beams. This dynamic positioning enables the system to capture both bright-field and dark-field radiographs by simply moving the grid, rather than requiring complex multiple recording geometries, thereby reducing measurement time while maintaining scattered radiation correction accuracy
Solution Approach 2:
The patent implements periodic action by alternating the grid structure between two distinct positions during the measurement process. In the first position, the grid transmits beams to capture bright-field radiographs; in the second position, the grid attenuates beams to capture dark-field radiographs. This periodic switching between positions allows the system to collect necessary data for scattered radiation correction through a streamlined single-geometry approach, reducing overall measurement time compared to methods requiring multiple fixed geometries
2Measurement precision
If grid structure is moved to different positions to capture scattered radiation, then correction precision improves, but device complexity increases
Solution Approach 1:
The patent uses the movable grid structure as an intermediary element between the x-ray source and detector. By positioning the grid at different locations along the beam path (first position for bright-field, second position for dark-field), it mediates the x-ray transmission to create the necessary contrast for scattered radiation correction. This intermediary approach simplifies the overall system compared to complex multi-geometry setups, as the grid's movement alone enables both measurement modes without requiring additional detectors or complex positioning mechanisms
Solution Approach 2:
The patent applies parameter changes by altering the grid's positional parameter along the beam path. Moving the grid between defined positions changes the beam attenuation parameters, enabling the system to switch between bright-field and dark-field measurement modes. This simple parameter change (grid position) provides an elegant solution that improves correction precision while avoiding the complexity of multiple recording geometries or additional hardware components
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for direct and precise capture of scattered radiation across all regions, enhancing correction accuracy and reducing measurement time and costs, particularly in industrial applications.
Implementation Method 1
dividing x-ray radiation emanating from the x-ray source into a plurality of partial beams via the grid structure in advance of the emanated x-ray radiation passing through a test object
Implementation Method 2
The x-ray detector is used to capture, with a spatial resolution, an x-ray intensity of the x-ray radiation following a passage through the test object in the form of a radiograph
Implementation Method 3
scattered radiation which is generated in adjacent volume elements and which has traveled a different path to the detector element
Data Source
AI summary
The invention is directed to a method for correcting scattered radiation in a computed tomography apparatus, wherein x-ray radiation emanating from an x-ray radiation source is divided into a plurality of partial beams by a grid structure such that irradiated regions and non-irradiated regions alternate, wherein a grid position of the grid structure is changed parallel to a detector surface. In a changed grid position, previously non-irradiated regions are irradiated and previously irradiated regions are not irradiated, wherein at least one radiograph of the test object is captured for each of the grid positions, wherein the radiographs captured at different grid positions are used to generate a bright field radiograph from the respectively irradiated regions and a dark field radiograph from the respectively non-irradiated regions and wherein a corrected radiograph is generated on the basis of the bright field radiograph and the dark field radiograph.